knitr::opts_chunk$set( collapse = TRUE, comment = "#>" )
Create a blank array and assign R object
# Sample data (~24 MB) x <- rnorm(3e6); dim(x) <- c(10, 100, 100, 30) # Save array to a path path <- tempfile() arr <- create_lazyarray(path, 'double', dim(x), multipart = TRUE) arr <- x
Load existing array
# Load existing array arr <- load_lazyarray(path)
The loaded array is read-only by default. However, they can be set writable.
# Make loaded array writable arr$make_writable() arr$can_write
arr$make_writable() dimnames(arr) <- list( A = 1:10, B = 1:100, C = 1:100, D = 1:30 )
# Subset/read array y1 <- arr y2 <- arr[,,,3] # Write to slice of data, writing to slices along the # last dimension is optimized arr[,,,1] <- seq_len(1e5)
sub <- subset(arr, A ~ A <= 2, B ~ B == 10) dim(sub)
Data created via
lazyarray does not remove automatically. You need to finalize array by yourself. This is because multiple lazy array instances might point to a same dataset. If one of the object is garbage collected, you might not want to remove the data on hard drive as this will invalidate the other instances. To manually remove data, use
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